As a method for producing resistors to be used in hybrid ICs and electronic apparatuses such as a thermal head, the thick-film system in which a resistor paste is coated on a substrate and then fired to produce a resistor, and a thin-film system using, for example, sputtering have heretofore been known, the former being described, for example, in Tobita et al., Proc. 1985 International Symposium on Microelectronics, entitled "Advanced Thick-film Techniques Applied for A New Thermal Printing Head", pp. 494-499, and Vest el al., Proc. 1983 International Symposium on Microelectronics, entitled "A General Gold Conductor From Metallo-Organic Compounds", pp. 62-68.
In accordance with the former method, a resistor paste prepared by dispersing a powdery mixture of ruthenium oxide and glass frit in an organic vehicle composed of a solvent and a resin is screen-printed on a substrate and then fired to produce a resistor.
The latter method utilizes vacuum technology. For example, a thin film of sparingly soluble metal such as tantalum is vacuum-deposited on a substrate by sputtering and a pattern is formed by the application of photolitho technique to produce a thin-film resistor. This thin-film resistor is used as a resistor for thermal heads.
Although the thick-film system using the conventional resistor paste has advantages in that the costs for the equipment for production of resistors are low and productivity is high, it suffers from disadvantages that the film thickness of resistors produced is as high as about 10 .mu.m or more, and since the thick film paste is a non-uniform mixture of glass first and ruthenium oxide powders, the strength against electric field is low, that is, when the voltage is changed, the resistance changes abruptly at a certain value. Further, the resistance of a resistor produced is difficult to control only by changing the ratio of glass powder to ruthenium oxide. The resistance greatly changes depending on a difference in particle diameter between glass powder and ruthenium oxide, and a firing temperature. Furthermore, even though the ratio and the average particle diameter are made equal in each lot, the resistance varies depending on the lot.
The latter thin-film system has problems that the equipment is expensive and productivity is low, although a uniform thin film resistor can be obtained.